FRAMEBORDER determines if there should be 3-D borders between the frames. YES, which is the default, says there should be borders. 1 is the same as YES.

NO says there should not be 3-D borders. Unfortunately, the name "FRAMEBORDER" is deceptive. With NO there are not cool 3-D borders, but there is still
the default background color (usually gray or white) between the frames:

To control how much space is between the frames (that is, how big are the borders) use
FRAMESPACING and
BORDER.
These are actually the same attribute; it's just that MSIE only understands
FRAMESPACING and Netscape only understands BORDER. Use both to be safe: